Tropical Deforestation and Climatic Change

Tropical deforestation, including both the permanent conversion of forests to croplands and pastures and the temporary or partial removal of forests for shifting cultivation and selective logging, is estimated to have released on the order of 1-2 PgC/yr (15-35% of annual fossil fuel emissions) during the 1990s. The magnitude of emissions depends on the rates of deforestation, the biomass of the forests deforested, and other reductions in biomass that result from forest use. If, in addition to carbon dioxide, one considers the emissions of methane, nitrous oxide, and other chemically reactive gases that result from deforestation and subsequent uses of the land, annual emissions during the 1990s accounted for about 25% of the total anthropogenic emissions of greenhouse gases. Trends in the rates of tropical deforestation are difficult to predict, but at today’s rates, another 85 to 130 PgC will be released over the next 100 years, the emissions declining only as tropical forests are eliminated.